MailMessage.Load(inputStream, MailMessageFormat.Msg)

GemBox.Email
1 
	readonly Dictionary<string, MailMessageFormat> EmailFormatMap = new Dictionary<string, MailMessageFormat>
	{
		{ "application/vnd.ms-outlook", MailMessageFormat.Msg },  // .msg formatı
		{ "message/rfc822", MailMessageFormat.Eml }              // .eml formatı
	};
MemoryStream inputStream = new MemoryStream();
FileManager.WriteToStream(FileContent, ref inputStream);
MailMessageFormat fileformat = EmailFormatMap.TryGetValue(ItemAttachment.FileType, out var format) ? format : MailMessageFormat.Eml;
var message = MailMessage.Load(inputStream, fileformat );

There is no problem when MailMessageFormat.Eml is passed as the second parameter to the Load method, but when MailMessageFormat.Msg is used, I get the following error.

System.Collections.Generic.KeyNotFoundException: 'The given key was not present in the dictionary

Thank you for your help!

2

Hi,

Please send us the MSG file that you’re loading into a MailMessage object so we can reproduce this issue and investigate it.

Regards,
Mario

3

Hi, I am currently evaluating Gembox.email and encountered the same issue when reading an Msg (Eml works fine): the given key ‘34068’ was not present in the dictionary. Any update on this?

4

Hi Johan,

Yes, this issue should be resolved in one of the newer versions.
Can you please try again with this latest package:

Install-Package GemBox.Email -Version 2025.4.110-hotfix

If the problem remains, please send us your MSG file so we can investigate it.

Regards,
Mario

5

Hi Mario,

Many thanks for the quick reply.
I can confirm that the fix works.

Best regards,
Johan